There are applications in orthopedic surgery, neurosurgery, and other medical treatments and operative procedures where a patient's head must be engaged and held in a predetermined position with respect to the patient's body. Very often, during healing of injuries involving fracture or dislocation of the cervical spine, a patient's head must be immobilized with respect to the patient's body in order to allow the fractured or dislocated bones to heal. For this purpose, halo traction units have been developed.
A halo traction unit comprises a halo, which rings the patient's head, a superstructure, and a vest, to which the superstructure is secured. The ring halo is held rigidly to the patient's head by "skull pins" which project through threaded holes in the halo and into the patient's skull. Thus the ring halo is held rigidly to the patient's head. The ring halo is then secured to the superstructure which in turn is secured to a vest which the patient wears on his or her chest. This structure maintains the head in a rigid, fixed relationship to the body.
While the patient's head is immobilized, it may be desirable to subject the patient to a magnetic resonance imaging machine (MRI, or NMR) or conventional x-rays, CAT scan, or other radiographic imaging tests. Therefore, it is desirable that the material for a halo be non-magnetic, and radio transparent, or at least that the material not interfere significantly with such tests.
When a patient initially enters a hospital directly from an accident scene, very often he or she will be strapped to a backboard or other head and neck immobilizing device. Based upon diagnostic results it may be desirable to attach a halo or skull tongs to provide traction and/or to immobilize the head and neck without moving the patient until the treatment has been applied. Many prior art halos are circular, and completely encircle the head of the patient. This makes impossible the application of the halo to the patient without removal of the patient from the backboard. Therefore, the patient's head must be moved or extended over the edge of the backboard or bed.
Recently, halos have been developed which have open backs, and which, therefore, allow application to the patient while the patient remains on a backboard or bed. However, due to the materials of construction and particular configurations of such open-backed halos, the open-backed halos are not extremely rigid. This instability is caused by removal of the back portion of the halo. As a result, the halo flexes when applied to and worn by the patient. This flexing results in movement of the skull pins against the skull and possible loosening of the skull pins. Such movement results in infections and other associated problems and should be eliminated. Preferably, one step toward elimination of these problems would be development of an open-backed halo with high rigidity.
Movement and loosening of skull pins is also caused by vibrations transmitted from the vest to the halo and patient's head through the superstructure and skull pins of the halo. The vibrations are caused simply by walking or other common movement. The transmission of these vibrations should also be reduced or eliminated to lessen the possibility of loosening of the skull pins.
If a patient is subjected to traction using skull tongs, prior art ring halos and open-backed halos require that the skull tongs be removed prior to application of the halo. It is undesirable to remove a patient from traction in this manner, and thus it would be preferable to apply a halo without removal of the skull tongs. This has heretofore been impossible.
Once a patient has been fitted with a halo, the halo is attached to a superstructure and vest worn by the patient, as previously explained. Generally, such attachment is accomplished by four vertical posts which run directly from the halo to a vest unit. Drawbacks with such a system include difficulty of adjusting of four separate posts to obtain even tension on the posts, and to obtain the correct position of the patient's head with respect to the patient's body. Further, such a unit is somewhat unnerving and distressing to patients. A superstructure which would provide simple adjustment without bulkiness would therefore be desirable.